I. Field of the Invention
The present invention relates generally to connecting devices, and in particular to a device for connecting, anchoring and tensioning the mounting straps of truck or trailer bed covers.
2. Description of the Related Art
Open-top truck and trailer beds and boxes are commonly designed so that cargo is loaded through their open tops and unloaded through their bottoms or backs. This sometimes creates the need for a cover to keep dust, moisture and other harmful substances from coming into contact with cargo that has been loaded into the truck or trailer bed or box. A cover may also be necessary to prevent cargo from blowing out of the truck or trailer body during high speed transportation. Regardless of whether cargo is loaded into the truck or trailer, a cover can enhance the aerodynamics of the truck or trailer during high speed transportation, thereby improving gas mileage.
Several coverings for open top cargo containers have been suggested. For example, the Sims U.S. Pat. No. 4,302,044 discloses rigid doors that pivot around hinges and are secured with mechanical fasteners. The Schmeichel et al U.S. Pat. No. 4,505,512 discloses a flexible tarp that is fixedly secured to one side of the open container, deployed across the top by a roll-up apparatus, and includes a mechanism to retain the roll bar when the tarp is in a covered position.
Where a flexible tarp is used to cover a cargo container opening, many systems for securing the tarp to the container involve the use of straps. For example, the Schmeichel et al. U.S. Pat. No. 4,505,512 discloses straps (60) that extend from the tarp (14) to a roll bar (64) which, in turn, is lodged in hooks (40) that secure the roll bar to the sidewall of the container. The Johnsen U.S. Pat. No. 4,212,492 discloses straps (90) that extend from the tarp cover edge (64) and are fastened by toggle action hooks (92) that secure the straps to the sidewall of the container. The Johnson U.S. Pat. No. 4,212,492 also discloses straps (94) that extend from the rear flap (40) of the tarp and are fastened by hooks (96) that secure the straps to the rear wall of the container.
Where straps extend from the edges of the tarp and are secured to the sidewalls of the cargo container, fastening devices are necessary to secure the straps. Such a fastening device should provide a secure means of attaching the flexible tarp to the cargo container to assure that the tarp will remain in place and intact. A fastening device should also allow easy operation to facilitate quick fastening and unfastening.
Another attribute of a fastening device should be to provide constant tensioning while the flexible tarp is covering the cargo container. For a variety of reasons, a tarp may stretch and tend to loosen. For example, the tarp may loosen due to exposure to the elements such as moisture. During high-speed transportation, the tarp may loosen due to aerodynamic forces exerted by wind passing over the tarp. Also, the tarp may loosen if cargo was initially loaded so as to be heaped above the normal height of the tarp; during transit, the load may settle resulting in a loose tarp. Without a means for constantly maintaining a uniformly tight cover and minimizing fabric movement, the tarp may start to flap, thereby resulting in excessive wear.
Current available fastening devices address some, but not all, of these problems. For example, some fastening devices involve arrangements that employ straps that are made of a resilient material that are fixedly secured to the sidewall of the container. An arrangement of this type is disclosed by the Johnsen U.S. Pat. No. 4,212,492 where the straps (94) are made of a resilient material such as bungy cord, and those straps are fastened by hooks (96) that secure the straps to be rear wall (20) of the container. This arrangement has the shortcoming that the straps may soon lose their resilient character, requiring frequent replacement. Once straps begin to lose their resilient character, the straps will provide less tensioning, thereby allowing the tarp to loosen and permitting fabric movement.
Other fastening devices involve arrangements that employ non-resilient straps that are manually tensioned before being fixedly secured to the sidewall of the container. An arrangement of this type is disclosed by the Johnsen U.S. Pat. No. 4,212,492 where the straps or cord (80) is manually trained through hooks (84, 86) before being fastened to a hook (88) that secures the cord to the sidewall (18) of the container. This arrangement has the shortcoming that it does not provide constant tensioning while the flexible top is covering the cargo container. If the tarp stretches and loosens after the straps are fixedly secured, there is no means to maintain a uniformly tight cover, and the tarp may start to flap, thereby resulting in excessive wear.
Other fastening devices involve arrangements that employ non-resilient straps that are mechanically tensioned before being fixedly secured to the sidewall of the container. An arrangement of this type is disclosed by the Johnsen U.S. Pat. No. 4,212,492 where the strap (90) is attached to a toggle action hook (92) which permits the strap to be tensioned as the toggle action hook is placed into a locked position (FIG. 6) and thereby secured to the sidewall (18).
Another arrangement of this type is anticipated by cargo strap tensioning devices that employ ratchet wheels as disclosed by Smetz et al. U.S. Pat. No. 4,622,721; Speich U.S. Pat. No. 4,584,742; Rutzki U.S. Pat. No. 4,542,883; van Iperen U.S. Pat. No. 4,510,652; and Holmberg U.S. Pat. No. 4,227,286. Another arrangement of this type is anticipated by truck platform locking devices that employ a lever whose locking means are activated by a spring as disclosed by Nilsson U.S. Pat. No. 4,493,133. Another arrangement of this type is anticipated by tensioning devices that employ a lever and a mechanical locking means as disclosed by Richmond U.S. Pat. No. 4,428,099; and Akaura U.S. Pat. No. 4,395,796. Yet another arrangement of this type is anticipated by a quick release load securement device that employs a tubular housing with a slide member and a lock pin as disclosed by Parnell et al. U.S. Pat. No. 4,314,783.
Arrangements Which involve mechanical tensioning prior to fixedly securing the strap to the sidewall of the container have the advantage of permitting greater tension than manual tensioning devices. Once fixedly secured, however, manual tensioning devices have the same shortcoming, viz., the arrangement does not provide constant tensioning while the flexible tarp is covering the cargo container. If the tarp stretches and loosens after the straps are fixedly secured, there is no means to maintain a uniformly tight cover, and the tarp may start to flap, thereby resulting in excessive wear.
Other fastening devices might involve arrangements that employ non-resilient straps that are mechanically tensioned after being fixedly secured to the sidewall of the container. An arrangement of this type is anticipated by the Parnell et al. U.S. Pat. No. 4,314,783 where a cargo securement band (36) is connected to a compression unit (38) which in turn is connected to a floor anchor (34). Such compression units are used with a separate toggle action fastener that typically is located at the other end of the cargo securement band, although the Parnell et al. U.S. Pat. No. 4,314,783 teaches (FIG. 10) a compression unit (38) that is located next to the fastening device (140).
Yet other fastening devices might involve arrangements that employ non-resilient straps that are mechanically tensioned before and after being fixedly secured to the sidewall of the container. An arrangement of this type is anticipated by load securement devices such as those shown in Neidigk U.S. Pat. No. 4,706,343 where a hydraulic arrangement is used as a fastening and tensioning device.
Arrangements that involve tensioning after fixedly securing the strap permit constant tensioning while the flexible tarp is covering the cargo container. Devices that might attain this attribute were designed to secure straps that hold and constrain heavy cargo loads such as heavy machinery or stacks of lumber placed upon the deck of a railroad flat car. As a consequence, devices that anticipate this type of arrangement are apt to be relatively expensive or complicated in operation. In expensive devices might be employed on only one side of the flexible tarp without obtaining a uniform tensioning o all sides of the tarp. If complicated in operation, the device may not allow quick fastening and unfastening.
The present invention addresses some or all of the aforementioned problems.